Zeitler started all 16 games for New York last season and has started all 31 games he played in the two years since joining the team in 2019 in a trade from the Cleveland Browns.
The move saves the Giants $12 million in cap space while leaving $2.5 million in dead cap for 2021, per Pat Leonard of the New York Daily News.
The money created an even bigger issue with the salary cap dropping to a reported $182.5 million in 2021, per Ian Rapoport of NFL Network.
Jordan Raanan of ESPN broke down the factors in the decision:
New York will still need help on the offensive line this offseason after giving up 50 sacks in 2020, tied for second most in the NFL.
Nate Solder could return after opting out of last season while 2020 first-round pick Andrew Thomas has high expectations, but the unit is still a weakness for a team hoping to improve upon its 6-10 record.
Zeitler should also draw interest on the open market as one of the most durable players in the NFL in recent years. The 31-year-old has missed just one game over the past six seasons with the Giants, Browns and Cincinnati Bengals and played 99 percent of New York's snaps in 2020.